A driving assistance device includes; a speed zone computation unit configured to compute a speed zone of the host vehicle having a possibility that the host vehicle will come into contact with the mobile object when progressing in the progressing direction, based on the mobile object information set by the mobile object information setting unit; a target speed computation unit configured to compute a target speed of the host vehicle based on a speed zone; and a target speed profile creation unit configured to create a target speed profile for decelerating the host vehicle from the current speed to the blind spot entry target speed, based on a blind spot entry target speed which is the target speed of the host vehicle at the time of entering a place forming the blind spot, a current speed of the host vehicle, and a target acceleration for deceleration.
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1. A driving assistance device comprising:
a blind spot recognition unit configured to recognize a blind spot of a driver in a progressing direction of a host vehicle;
a mobile object information setting unit configured to set mobile object information including at least an assumed speed of a mobile object, as information on the mobile object having a possibility of appearing suddenly from the blind spot;
a speed zone computation unit configured to compute a speed zone of the host vehicle having a possibility that the host vehicle will come into contact with the mobile object when progressing in the progressing direction, based on the mobile object information set by the mobile object information setting unit;
a target speed computation unit configured to compute a target speed of the host vehicle based on a speed zone; and
a target speed profile creation unit configured to create a target speed profile for decelerating the host vehicle from the current speed to the blind spot entry target speed, based on a blind spot entry target speed which is the target speed of the host vehicle at the time of entering a place forming the blind spot, a current speed of the host vehicle, and a target acceleration for deceleration,
wherein the target speed profile creation unit is configured to create the target speed profile, based on the target acceleration which is constant, a first target position in which a speed of the host vehicle is set as the blind spot entry target speed in front of the blind spot, and a second target position in which deceleration according to the target acceleration is started,
wherein the target speed profile creation unit is configured to create the target speed profile using at least one computation method, among a first computation method which computes the first target position and the second target position after the target acceleration is set, a second computation method which computes the target acceleration and the second target position after the first target position is set, and a third computation method which computes the target acceleration and the first target position after the second target position is set, and
wherein the target speed profile creation unit is configured to study characteristics of the driver, and to determine one computation method, among the first computation method, the second computation method, and the third computation method, based on the characteristics of the driver.
2. The driving assistance device according to
wherein the target speed profile creation unit is configured to create the target speed profile by computing a contact point of a boundary line of the speed zone and the target speed profile.
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This is a national phase application based on the PCT International Patent Application No. PCT/JP2012/056741 filed Mar. 15, 2012, the entire contents of which are incorporated herein by reference.
The present invention relates to a driving assistance device.
As a driving assistance device of the related art, the device has been known that performs driving assistance in consideration of an object appearing suddenly from a blind spot, when entering an intersection or the like. For example, the driving assistance device described in Patent Literature 1 predicts a course of a host vehicle, recognizes a blind spot of a driver in a progressing direction of the host vehicle, predicts an object having a possibility of appearing suddenly from the blind spot, detects a range in which the object can move, determines that there is a possibility of the collision when the range and a predicted path of the host vehicle overlap each other, and performs the driving assistance so as to avoid the collision.
However, a driving assistance device of the related art performs driving assistance, using a course prediction result of a host vehicle. Thus, the driving assistance device of the related art determines whether or not a collision will occur when travelling according to a predicted course of the present situation, thereby avoiding the collision. But the driving assistance device cannot compute the amount of speed decrease that is required for collision avoidance, the amount of avoidance that is required, or the like. In addition, a collision determination of the driving assistance device of the related art depends on the prediction accuracy of a future position of the host vehicle. Thus, in a case where the prediction accuracy is low (for example, while the host vehicle is accelerated, decelerated, or being steered), there is a possibility that accuracy of the collision determination will be low. In this case, the driving assistance device of the related art performs unnecessary driving assistance, or does not perform the driving assistance at the necessary timing, and thus there is a possibility of giving a sense of discomfort to a driver.
The present invention is made to solve such a problem, and an object of the present invention is to provide a driving assistance device which performs an appropriate driving assistance and can improve safety even more.
A driving assistance device includes a blind spot recognition unit configured to recognize a blind spot of a driver in a progressing direction of a host vehicle; a mobile object information setting unit configured to set mobile object information including at least an assumed speed of a mobile object, as information on the mobile object having a possibility of appearing suddenly from the blind spot; a speed zone computation unit configured to compute a speed zone of the host vehicle having a possibility that the host vehicle will come into contact with the mobile object when progressing in the progressing direction, based on the mobile object information set by the mobile object information setting unit; a target speed computation unit configured to compute a target speed of the host vehicle based on a speed zone; and a target speed profile creation unit configured to create a target speed profile for decelerating the host vehicle from the current speed to the blind spot entry target speed, based on a blind spot entry target speed which is the target speed of the host vehicle at the time of entering a place forming the blind spot, a current speed of the host vehicle, and a target acceleration for deceleration.
In the driving assistance device, the mobile object information setting unit predicts the mobile object having a possibility of appearing suddenly from the blind spot, and sets the mobile object information on the mobile object. In addition, the speed zone computation unit can compute the travel speed of the host vehicle having a possibility of the collision with the mobile object, based on the assumed speed of the mobile object predicted to rush out of the blind spot. Subsequently, the speed zone computation unit can compute the speed zone having a possibility that the host vehicle will come into contact with the mobile object, as the speed zone of the host vehicle. The target speed computation unit computes the target speed, based on the computed speed zone. By doing so, the driving assistance device does not compare the assumed mobile object with the course prediction result of the host vehicle, computes the speed zone having a possibility of contacting the mobile object, and computes the target speed based on the computation. In this way, the driving assistance device can perform the control based on the specific target speed which is a speed appropriate to travel, and thus the driving assistance with a high level of safety can be ensured to be performed. In addition, the driving assistance according to the driving assistance device is not influenced by the accuracy of the course prediction of the host vehicle, and thus an appropriate driving assistance can be performed. Furthermore, the driving assistance device includes the target speed profile creation unit which creates the target speed profile for decelerating the host vehicle from the current speed to the blind spot entry target speed at the time of entering the place forming the blind spot. Thus, the driving assistance device can perform finally the driving assistance in which it is considered not only at which speed the host vehicle may enter the place forming the blind spot but also how much the host vehicle may decelerate while reaching there. Accordingly, a more appropriate driving assistance can be performed. As described above, the driving assistance device performs an appropriate driving assistance and can improve the safety even more.
In the driving assistance device, the target speed profile creation unit may be configured to create the target speed profile by computing a contact point of a boundary line of the speed zone and the target speed profile. For example, when the driving assistance is performed according to the target speed profile which avoids too much the speed zone in which there is a possibility that the host vehicle contacts the mobile object, there is a case where the driver feels cumbersome. However, since the target speed profile creation unit creates the target speed profile by computing the contact point of the boundary line of the speed zone and the target speed profile, the safety is ensured in such a manner that the speed of the host vehicle does not enter the speed zone, and it is possible to suppress the cumbersome feeling due to an excessive driving assistance.
In the driving assistance device, the target speed profile creation unit may be configured to create the target speed profile, based on the target acceleration which is constant, a first target position at which a speed of the host vehicle is set as the blind spot entry target speed in front of the blind spot, and a second target position at which deceleration according to the target acceleration is started. Accordingly, the target speed profile creation unit starts the deceleration according to the constant acceleration at the second target position, and in a state where the blind spot entry target speed is set at the first target position in front of the blind spot, can create the target speed profile such as that for entering the blind spot. Accordingly, the driving assistance device can perform the driving assistance in which the speed profile of the driver is realized with a high and safe driving technology.
In the driving assistance device, the target speed profile creation unit may be configured to create the target speed profile using at least one computation method, among a first computation method which computes the first target position and the second target position after the target acceleration is set, a second computation method which computes the target acceleration and the second target position after the first target position is set, and a third computation method which computes the target acceleration and the first target position after the second target position is set. Accordingly, it is possible to create the target speed profile using an appropriate computation method depending on the situation.
In the driving assistance device, the target speed profile creation unit may be configured to study characteristics of the driver, and to determine one computation method, among the first computation method, the second computation method, and the third computation method, based on the characteristics of the driver. Accordingly, it is possible to create the target speed profile using an appropriate computation method depending on the characteristics of the driver, and to perform the driving assistance in which a sense of discomfort to the driver is reduced.
According to the present invention, it is possible to perform an appropriate driving assistance and to improve safety even more.
Hereinafter, an embodiment of a driving assistance device will be described with reference to the drawings.
As illustrated in
The vehicle exterior information acquisition unit 3 functions to acquire information on the exterior of the vicinity of the host vehicle SM. Specifically, the vehicle exterior information acquisition unit 3 functions to acquire various information on a structure forming a blind spot around the host vehicle SM, a moving object such as the vehicle, a pedestrian, or a bicycle, a white line or a stop line around the intersection, or the like. For, example, the vehicle exterior information acquisition unit 3 is configured by a camera acquiring an image around the host vehicle SM, a millimeter wave radar, a laser radar, or the like. For example, the vehicle exterior information acquisition unit 3 can detect objects such as the structures on both sides of the traffic lane or the vehicle, by detecting edges that exist around the vehicle using the radar. In addition, for example, the vehicle exterior information acquisition unit 3 can detect the white line around the host vehicle SM, the pedestrian or the bicycle using the image captured by the camera. The vehicle exterior information acquisition unit 3 outputs the acquired vehicle exterior information to the ECU 2.
The vehicle interior information acquisition unit 4 functions to acquire information on the interior of the host vehicle SM. Specifically, the vehicle interior information acquisition unit 4 can detect the position of the driver DP in the host vehicle SM, the direction of the head, the direction of the sight line, or the like. For example, the vehicle interior information acquisition unit 4 is configured by a camera which is provided around the driver's seat and captures the driver DP, or the like. The vehicle interior information acquisition unit 4 outputs the acquired vehicle interior information to the ECU 2.
The navigation system 6 includes various information such as map information, road information or traffic information. The navigation system 6 outputs predetermined information to the ECU 2 at the required timing. The information storage unit 7 functions to store various information, for example, can store past driving information of the driver DP. The information storage unit 7 outputs the predetermined information to the ECU 2 at the required timing.
The display unit 8, the voice generation unit 9, and the travel assistance unit 11 function to assist the driving of the driver DP according to a control signal output from the ECU 2. For example, the display unit 8 is configured by a monitor, a head-up display or the like, and functions to display information for driving assistance. The voice generation unit 9 is configured by a speaker, a buzzer or the like, and functions to generate a voice or a buzzer sound for the driving assistance. The travel assistance unit 11 is configured to have a braking device, a driving device and a steering device, and functions to decelerate to a target speed or functions to move to a target position.
The ECU 2 is an electronic control unit which performs a control of the entire driving assistance device 1, for example, configures a CPU as a main body, and includes a ROM, a RAM, an input signal circuit, an output signal circuit, a power supply circuit or the like. The ECU 2 includes a blind spot recognition unit 21, a mobile object information setting unit 22, a speed zone computation unit 23, a target speed computation unit 24, a target lateral position computation unit 25, a traffic information acquisition unit 26, an experience information acquisition unit 27, an object information acquisition unit 28, a viewing direction detection unit 29, a driving assistance control unit 31, and a target speed profile creation unit 32.
The blind spot recognition unit 21 functions to recognize a blind spot of the driver DP in the progressing direction of the host vehicle SM. The blind spot recognition unit 21 acquires the position of the host vehicle SM, the driver DP, the position of the intersection (and the structure forming the blind spot) of the traffic lanes LD1 and LD2 or the like from the various information acquired by the vehicle exterior information acquisition unit 3 and the vehicle interior information acquisition unit 4, and can recognize the blind spot from a positional relationship to one another. In the example of
The mobile object information setting unit 22 functions to set mobile object information on a mobile object which may rush out of the blind spot. For example, the mobile object information includes the information on an assumed speed of the mobile object, an assumed position and an assumed size. In the example of
The speed zone computation unit 23 has a possibility that the host vehicle SM will come into contact with the mobile object when progressing in the progressing direction, and functions to compute the speed zone of the host vehicle SM, based on the mobile object information set by the mobile object information setting unit 22. The speed zone is determined by a relationship between the speed of the host vehicle SM and the distance of the host vehicle SM with respect to a reference position in a place forming the blind spot. Specifically, as illustrated in
The target speed computation unit 24 functions to compute a target speed of the host vehicle SM, based on the speed zone computed by the speed zone computation unit 23, namely, the danger zone DZ. The target speed computation unit 24 sets the target speed so as to avoid the danger zone DZ. The target speed computation unit 24 computes the speed at which the host vehicle does not enter the danger zone DZ and sets the computed speed as the target speed, when the host vehicle SM passes through the blind spot entry point SDL. A method of setting the target speed will be described later.
The target lateral position computation unit 25 functions to compute a target lateral position of the host vehicle SM, based on the speed zone computed by the speed zone computation unit 23, namely, the danger zone DZ. The target lateral position computation unit 25 computes a lateral position at which safety can be increased, and sets the computed lateral position as the target lateral position, when the host vehicle SM passes through the blind spot entry point SDL. A method of setting the target lateral position will be described later.
The traffic information acquisition unit 26 functions to acquire information on the road forming the blind spot, namely, the intersection that the host vehicle SM is about to enter. The traffic information acquisition unit 26 can acquire traffic information from the navigation system 6 or the information storage unit 7. For example, the traffic information includes an average traffic volume of the other side road, the number and frequency of past accidents, the number of pedestrians, and the like.
The experience information acquisition unit 27 functions to acquire past experience information of the driver DP. The experience information acquisition unit 27 acquires information from the information storage unit 7. For example, the experience information includes the number of times and frequency that the driver DP has ever passed through a target intersection, the time that has elapsed since the passage, or the like.
The object information acquisition unit 28 functions to acquire object information on behavior of an object present around the host vehicle SM. The object is not particularly limited to things that influence the mobile object in the traffic lane of the other side. For example, a preceding vehicle, an oncoming vehicle, a pedestrian, a motorcycle, a bicycle, or the like can be used as the object. The object information includes the information on a position, a size, a moving direction, a moving speed, or the like of the object described above. The object information acquisition unit 28 can acquire the object information from the vehicle exterior information acquisition unit 3.
The viewing direction detection unit 29 functions to detect a viewing direction of the driver DP. The viewing direction detection unit 29 acquires information from the vehicle interior information acquisition unit 4, and can detect a viewing direction from a sight line or a face orientation of the driver DP.
The driving assistance control unit 31 functions to control a driving assistance by transmitting control signals to the display unit 8, voice generation unit 9, and the travel assistance unit 11 based on various computation results. The driving assistance control unit 31 functions to perform the driving assistance, in such a manner that the host vehicle enters the intersection using the target speed or the target lateral position. The detailed assistance method will be described later. In addition, when the blind spots exist in a plurality of directions, the driving assistance control unit 31 functions to determine a danger direction with a high degree of danger, based on the shape of the speed zone (danger zone DZ) computed by the speed zone computation unit 23. In addition, the driving assistance control unit 31 functions to get the attention of the driver DP using the display unit 8 or the voice generation unit 9, so as to allow the driver DP to turn to the danger direction.
The target speed profile creation unit 32 has a function to create a target speed profile VPR with respect to the danger zone DZ. The target speed profile creation unit 32 creates the target speed profile VPR based on a blind spot entry target speed which is the target speed of the host vehicle SM at the time of entering a position (blind spot entry point SDL in the present embodiment) forming the blind spot, a current speed of the host vehicle, and a target acceleration for deceleration. The target speed profile VPR depicts a trajectory of the target speed for decelerating the host vehicle SM from the current speed to the blind spot entry target speed. In an example illustrated in
The target speed profile creation unit 32 creates the target speed profile VPR by computing a contact point T of a danger zone entry line DA which is a boundary line on an entry side of the danger zone DZ, and the target speed profile VPR. In addition, the target speed profile creation unit 32, in addition to the blind spot entry target speed, the current speed and the target acceleration, creates the target speed profile VPR based on a first target position (position of a distance L1 in the graph of
Next, specific control processing of the driving assistance device 1 will be described with reference to
As illustrated in
The blind spot recognition unit 21 determines whether or not the distance (or the distance between the current position of the host vehicle SM and the blind spot entry point SDL) between the current position of the host vehicle SM and the blind spots DE1 and DE2 is less than or equal to a predetermined threshold value TL, based on the blind spot DE1 and DE2 recognized in step S100 (step S105). In step S105, if the distance is determined to be greater than the threshold value TL by the blind spot recognition unit 21, the processing illustrated in
The mobile object information setting unit 22 predicts a mobile object having a possibility of appearing suddenly from the blind spots DE1 and DE2, and sets the mobile object information on the mobile object (step S110). In
An assumption method of the assumed speed is not particularly limited. For example, in consideration of the traffic lane width of the traffic lane LD2 of the other side, or the like, a legal speed on the road may be set as the assumed speed, an average entry vehicle speed may be set as the assumed speed based on the past statistics, and the same speed as the host vehicle SM may be set as the assumed speed. An assumption method of the assumed position (assumed lateral position) is not particularly limited. For example, a central position of the travel lane may be set as the assumed position, an average entry vehicle position may be set as the assumed position based on the past statistics, and the same position as the host vehicle SM may be set as the assumed position. In addition, an assumption method of the assumed size of the other vehicle is not particularly limited as well. For example, data that is prepared as a general vehicle size in advance may be set as the assumed size, an average size of a general car may be set as the assumed size, and the same size as the host vehicle SM may be set as the assumed size.
In addition, the mobile object information setting unit 22 may set the mobile object information, based on a road shape (namely the intersection shape) forming the blind spots DE1 and DE2. For example, in a T-shaped intersection as illustrated in
In addition, the mobile object information setting unit 22 may set the mobile object information, based on the ratio of the traffic lane width of the other vehicle side and the traffic lane of the host vehicle side. For example, when a priority road of the host vehicle side is a large road and the priority road of the other side is a small road, the vehicle on the other side hesitates to enter the intersection without decelerating. On the other hand, when the road of the host vehicle side is the same size as the road of the other side or the road of the other side is larger than that of the host vehicle side, the vehicle on the other side tends to enter the intersection without decelerating. Thus, the mobile object information setting unit 22 sets the assumed speed of the other vehicle by considering the ratio of the traffic lane width of the other vehicle side and the traffic lane width of the host vehicle side, based on the map as illustrated in
In addition, the mobile object information setting unit 22 may set the mobile object information, based on the surrounding environment of the blind spots DE1 and DE2. In other words, the mobile object information setting unit 12 sets not only the shape of the intersection but also movement information of the other vehicle, based on the surrounding environment of the blind spots DE1 and DE2. For example, when there is a curve mirror at the intersection, it can be determined that the speed of the other vehicle is decreased. In addition, when the stop line in the traffic lane of the other vehicle on the other side is close to the intersection and the stop line is seen from the host vehicle, it can be determined that a deceleration point of the other vehicle is delayed. In this case, it can be determined that the deceleration is not performed if the other vehicle is not close to the intersection and eventually the intersection entry speed is increased. On the other hand, when the stop line in the traffic lane of the other vehicle on the other side is far from the intersection and the stop line is at a position not seen from the host vehicle, it can be determined that a deceleration point of the other vehicle is quick. In this case, it can be determined that the other vehicle performs the deceleration at an early stage and thus eventually the intersection entry speed is decreased. In addition, for example, when a white line such as a side strip extends on both sides of the traffic lane LD1 of the host vehicle side which is a priority traffic lane and the white line extends to even part of the traffic lane LD2 of the other side without interruption, the other vehicle on the other side tends to decelerate. As described above, the mobile object information setting unit 22 may set the mobile object information, based on the surrounding environment which is likely to influence the behavior of the other vehicle. In this way, by considering the surrounding environment of the blind spot, the driving assistance device 1 can perform the driving assistance which is more appropriate for the driver's sense.
In addition, the mobile object information setting unit 22 may set the mobile object information, based on the traffic information acquired by the traffic information acquisition unit 26. For example, since special attention is required at the intersection in which the average traffic volume of the other side road, the number and frequency of the past accidents or the like is high, there occurs necessity for strictly setting the mobile object information. In addition, at the intersection in which the number of pedestrians or the like is high, the speed of the other vehicle on the other side tends to be delayed. The mobile object information setting unit 22 may set the mobile object information by considering the influence of the traffic information as described above. By considering the traffic information which cannot be known only by the information around the blind spot, the driving assistance device 1 can perform valid driving assistance capable of reliably ensuring safety, when the host vehicle passes through a blind spot road with a really high degree of danger.
The mobile object information setting unit 22 may set the mobile object information, based on the experience information acquired by the experience information acquisition unit 27. For example, when the number of times and frequency that the driver DP has ever passed through the target intersection are low, the mobile object information is strictly set in order to give the driver DP attention. In addition, when a long period of time has elapsed after the host vehicle passed through the intersection, the mobile object information is strictly set. The mobile object information setting unit 22 may set the mobile object information in consideration of the influence of the above-described experience information. By using the past experience information of the driver in this way, the driving assistance device 1 can perform the driving assistance which is appropriate to the driver's experience.
In addition, the mobile object information may be set based on the object information acquired by the object information acquisition unit 28. For example, when the object such as a preceding vehicle, an oncoming vehicle, a pedestrian, a motorcycle, or a bicycle enters (or entry can be predicted) the blind spot entry point a predetermined time earlier than the host vehicle SM, the other vehicle of the other side decelerates. The mobile object information setting unit 22 may set the mobile object information in consideration of the behavior of a surrounding object. The behavior of the surrounding object of the host vehicle even influences speed or the like of the mobile object which rushes out. However, the driving assistance device 1 can perform more definite and more appropriate driving assistance, by considering such information.
Next, the speed zone computation unit 23 computes the danger zone based on the mobile object information set in step S110 (step S120). Even though the mobile object rushes out of the blind spot, the speed zone computation unit 23 computes the danger zone by computing the condition that the host vehicle can pass through the intersection without the collision with the mobile object. Specifically, the speed zone computation unit 23 computes “condition A: the condition that the host vehicle SM can pass earlier than the other vehicle RM appearing suddenly from the blind spot DE1 on the right”, “condition B: the condition that the other vehicle RM can pass earlier than the other vehicle RM appearing suddenly from the blind spot DE1 on the right”, “condition C: the condition that the host vehicle SM can pass earlier than the other vehicle LM appearing suddenly from the blind spot DE2 on the left”, and “condition D: the condition that the other vehicle LM can pass earlier than the other vehicle LM appearing suddenly from the blind spot DE2 on the left”. Here, the speed V of the host vehicle SM which is a vertical axis of the coordinate in
<Condition A>
Here, the distance LR is an unknown quantity, but a right-angled triangle drawn from a positional relationship between the driver DP and the corner P1 and a right-angled triangle drawn from a positional relationship between the driver DP and the corner P3 are in a relationship similar to each other. Thus, the relationship of a formula (1A) is established from the dimensional relationship illustrated in
LR+(B/2−BD):W2−BD=L+AD+WR+BR/2:L+AD (1A)
(LR+B/2−BD)(L+AD)=(W2−BD)(L+AD+WR+BR/2) (2A)
LR={(W2−BD)(L+AD+WR+BR/2)−(B/2−BD)(L+AD)}/(L+AD) (3A)
tR
VA≧(A+L+WR+BR/2)/tR
The speed zone computation unit 23 specifies a zone that satisfies the condition A in the coordinate illustrated in
<Condition B>
Here, the distance LR is an unknown quantity, but a right-angled triangle drawn from a positional relationship between the driver DP and the corner P1 and a right-angled triangle drawn from a positional relationship between the driver DP and the corner P3 are in a relationship similar to each other. Thus, the relationship of a formula (1B) is established from the dimensional relationship illustrated in
LR+(AR+B/2+BD):W2−BD=L+AD+WR+BR/2:L+AD (1B)
{LR−(AR+B/2+BD)}(L+AD)=(W2−BD)(L+AD+WR+BR/2) (2B)
LR={(W2−BD)(L+AD+WR+BR/2)+(AR+B/2+BD)(L+AD)}/(L+AD) (3B)
tR
VB≦L+WR−BR/2)/tR
The speed zone computation unit 23 specifies a zone that satisfies the condition B in the coordinate illustrated in
<Condition C>
Here, the distance LL is an unknown quantity, but a right-angled triangle drawn from a positional relationship between the driver DP and the corner P2 and a right-angled triangle drawn from a positional relationship between the driver DP and the corner P4 are in a relationship similar to each other. Thus, the relationship of a formula (1C) is established from the dimensional relationship illustrated in FIG. 6(b). A formula (2C) is figured out by developing the formula (1C), and thereby the distance LL is represented by a formula (3C). If the time when the other vehicle LM reaches the position LMC is referred to as tL
LL+B/2+BD:W1−BD=L+AD+WL+BL/2:L+AD (1C)
(LL+B/2+BD)(L+AD)=(W1+BD)(L+AD+WL+BL/2) (2C)
LL={(W1+BD)(L+AD+WL+BL/2)−(B/2+BD)(L+AD)}/(L+AD) (3C)
tL
VC(A+L+WL+BL/2)/tL
The speed zone computation unit 23 specifies a zone that satisfies the condition C in the coordinate illustrated in
<Condition D>
Here, the distance LL is an unknown quantity, but a right-angled triangle drawn from a position relationship between the driver DP and the corner P2 and a right-angled triangle drawn from a position relationship between the driver DP and the corner P4 are in a relationship similar to each other. Thus, the relationship of a formula (1D) is established from the dimensional relationship illustrated in
LL−(AL+B/2−BD):W2+BD=L+AD+WL+BL/2:L+AD (1D)
{LL−(AL+B/2−BD)}(L+AD)=(W1+BD)(L+AD+WL+BL/2) (2D)
LL={(W1+BD)(L+AD+WL+BL/2)+(AL+B/2−BD)(L+AD)}/(L+AD) (3D)
tL
VD≦L+WL−BL/2)/tL
The speed zone computation unit 23 specifies a zone that satisfies the condition D in the coordinate illustrated in
Based on the above-described computation, the speed zone computation unit 23 sets the speed zone of max (VB, VD)<V<min (VA, VC) as the danger zone DZ, as illustrated in
Here, the danger zone will be described. When the host vehicle SM reaches a position of a predetermined distance L, it is assumed that the speed V of the host vehicle SM is in the danger zone DZ. In this state, when the other vehicles RM and LM rush out of the blind spots DE1 and DE2 at the next instant, if the host vehicle SM travels at a constant speed in a constant lateral position by the speed V, the host vehicle SM can come into contact with the other vehicles RM and LM. If the other vehicles RM and LM rush out, it causes the host vehicle SM to perform sudden braking or a sudden steering. In other words, when a speed condition of the host vehicle SM is in the danger zone DZ, and when the other vehicles RM and LM rush out of the blind spots DE1 and DE2 at the next instant, there is a possibility of the collision. Thus, it is preferred that the host vehicle SM travels by avoiding the danger zone DZ.
Specifically, as illustrated in
Next, the target lateral position computation unit 25 computes the target lateral position of the host vehicle SM, based on the danger zone DZ computed in step S120 (step S130). As illustrated in
When the processing of step S130 is performed, the speed zone computation unit 23 computes the danger zone DZ with respect to the side spaces (W1, W2) of a plurality of patterns in advance and stores the computed danger zone as a map. In addition, since the speed zone computation unit 23 can specify the blind spots DE1 and DE2 using a computation, even under a positional condition different from the actual position of the host vehicle SM while computing, the danger zone DZ with respect to the side spaces (W1, W2) of the plurality of patterns can be computed.
An example of a map is illustrated in
The target lateral position computation unit 25 sets an optimal target lateral position, based on the map illustrated in
Next, the target speed computation unit 24 computes the target speed Vtarget of the host vehicle SM, based on the danger zone DZ computed in step S120 (step S140). The target speed computation unit 24 sets the speed which can avoid the danger zone DZ regardless of the distance L, as the target speed Vtarget. Here, the target speed computation unit 24 sets a smaller value of max (VB) and max (VD) in the lower limit value (the maximum value in the lower speed than that in the danger zone) of the danger zone, namely, in L=0, as the target speed Vtarget. In
Next, the driving assistance control unit 31 determines whether there is a necessity of the driving assistance, based on the target lateral position computed in step S130, the target speed computed in step S140, and the actual lateral position and speed of the host vehicle SM (step S150). Specifically, the driving assistance control unit 31 determines whether or not the current side space W1now of the host vehicle SM is different from the target side space W1target (the difference is larger than the threshold value). When the current side space is determined to be equal to the target side space, the driving assistance control unit 31 determines that the driving assistance for the lateral position adjustment is not required. When the current side space is determined to be different from the target side space, the driving assistance control unit 31 determines that the driving assistance for the lateral position adjustment is required. In addition, the driving assistance control unit 31 determines whether or not the current speed Vnow of the host vehicle SM is higher than the target speed Vtarget. When the current speed Vnow is determined to be lower than the target speed Vtarget, the driving assistance control unit 31 determines that the driving assistance for the speed adjustment is not required. When the current speed Vnow is determined to be higher than the target speed Vtarget, the driving assistance control unit 31 determines that the driving assistance for the speed adjustment is required. In step S150, when no driving assistance is determined to be required, the control processing illustrated in
When it is determined that the driving assistance is required in step S150, the target speed profile creation unit 32 creates the target speed profile VPR with respect to the danger zone DZ (step S170). In addition, in the present embodiment, the target speed Vtarget computed in step S140 corresponds to the target speed at the blind spot entry point SDL (L=0), that is, the blind spot entry target speed which is the speed of the host vehicle SM at the time of entering the position forming the blind spot. In addition, the speed Vnow is the current speed of the host vehicle SM. Thus, hereinafter, description will be made by referring to these as “blind spot entry target speed Vtarget” and “current speed Vnow”. In addition, in the following description, with reference to
The target speed profile creation unit 32 first sets the target acceleration a (a<0 because of deceleration) for performing a deceleration assistance. The target acceleration a is set as a constant acceleration. As the target acceleration a, a value which is set in advance, a value in accordance with the driver, or the like can be used. As illustrated in a graph on a lower side of
Based on the current speed Vnow, the blind spot entry target speed Vtarget, and the target acceleration a, the target speed profile creation unit 32 computes a contact point T (L=L3) when the uniform acceleration deceleration line PR2 contacts a danger zone entry line DA in the danger zone DZ, the first target position (L=L1), and the second target position (L=L2). The danger zone entry line DA is formed in a boundary line which contacts an area in which a point of the current speed Vnow exists, among the boundary lines which determine the danger zones DZ. In addition, the danger zone entry line DA (boundary line) may by a curve or a straight line which determines the danger zone DZ, and may be an approximate line which is set with respect to the curve or the straight line. When the danger zone DZ is determined as illustrated in
V=b×L+Vtarget=fDA(L) (6)
V=√{−2a×(L−L1)}+Vtarget=fC(L). (7)
A condition for the danger zone entry line DA contacting the uniform acceleration deceleration line PR2 is that the speeds V of both and differentiated values thereof become equal, in the contact point T (L=L3). That is, the following formulas (8) and (9) are established. In addition, if fC(L) is differentiated with respect to a distance L, a formula (10) is established.
fDA(L3)=fC(L3) (8)
f′DA(L3)=f′C(L3) (9)
f′C(L)=−a√{−2a×(L−L1)} (10)
By using the formula (6) and the formula (7), the formula (8) is represented by a formula (11), and the formula (9) is represented by a formula (12). In addition, from the formula (11) and the formula (12), the position (L=L3) of the contact point T is computed as represented by a formula (13), and the first target position (L=L1) at which the speed V of the host vehicle SM becomes the blind spot entry target speed Vtarget is computed as represented by a formula (14).
b×L3+VAtarget=√{−2a×(L3−L1)}+Vtarget (11)
b=−a/√t{−2a×(L3−L1)} (12)
L3=−a/b2 (13)
L1=−a/2/b2 (14)
In addition, since the speed V is the current speed Vnow at the second position (L=L2) at which the deceleration is started, a formula (15) is established by assigning L=L2 and V=Vnow to the formula (7), and the second target position (L=L2) such as represented by a formula (16) is computed from the formula (15).
Vnow=√{−2a×(L2−L1)}+Vtarget (15)
L2=(Vnow−Vtarget)2/(−2a)+L1 (16)
As a result, the target speed profile VPR is represented by the following formula (17).
V=Vnow(L>L2)
V=√{−2a×(L−L1)}+Vtarget
(L2≧L>L1)
V=Vtarget(L1≧L) (17)
In addition, the target speed profile creation unit 32 may use the second computation method which first sets the first target position (L=L1), and computes the target acceleration a and the second target position (L=L2) based on the setting. In addition, the target speed profile creation unit 32 may use the third computation method which first sets the second target position (L=L2), and computes the target acceleration a and the first target position (L=L1) based on the setting. When the second computation method and the third computation method are employed, the target speed profile creation unit 32 calculates each computation value using a computation method with the same principles as those of the above-described formula (6) to formula (17).
In addition, the target speed profile creation unit 32 studies the characteristics of the driver, and may determine one computation method, among the first computation method, the second computation method, and the third computation method, based on the characteristics of the driver. The speed profile at the time of entering the intersection changes in characteristics depending on the driver, and a computation method corresponding to such characteristics can be employed. With respect to a driver with characteristics in which acceleration may be said to decrease constantly, the first computation method of setting the target acceleration a is employed. The deceleration is performed at a position a predetermined distance before the blind spot entry position SDL up to the target speed, and with respect to a driver with characteristics in which a distance may be said to be constant, the second computation method of setting the first target position (L=L1) is employed. The deceleration is started at a position a predetermined distance before the blind spot entry position SDL, and with respect to the driver with the characteristics in which the distance may be said to be constant, the third computation method of setting the second target position (L=L2) is employed. Specifically, in daily driving, the target speed profile creation unit 32 analyzes what kind of speed profile will be depicted when the host vehicle SM enters the intersection, calculates a value corresponding to the above-described a, L1, and L2, and stores the calculated value in the information storage unit 7. In addition, the target speed profile creation unit 32 calculates dispersion values of the values of the a, L1, and L2, and according to the smallest value (that is, the value tends to be constant) of standardized dispersion values (which are obtained by dividing the dispersion values by a maximum value), determines which of the first computation method, the second computation method, and the third computation method to employ.
The driving assistance control unit 31, based on the result determined in step S150, performs a driving assistance for moving the host vehicle SM to the target lateral position, and a driving assistance for setting the speed of the host vehicle SM to the target speed (step S160). In the present embodiment, the driving assistance control unit 31 performs the driving assistance such as the deceleration, according to the target speed profile created in step S170. For example, the driving assistance control unit 31 may decelerate forcibly according to the target speed profile by controlling the travel assistance unit 11. In addition to this, the driving assistance control unit 31 may perform a notification to the effect that it is decelerating to the target speed Vtarget with respect to the driver DP through the display unit 8 or the voice generation unit 9, or a notification to the effect that it is decelerating according to the target speed profile. The driving assistance control unit 31 may move forcibly the host vehicle SM to the target side space W1target by controlling the travel assistance unit 11. Alternatively, the driving assistance control unit 31 may perform a notification to the effect that the host vehicle SM is moving to the target side space W1target with respect to driver DP through the display unit 8 or the voice generation unit 9. In addition, as the driving assistance regarding the lateral position, only one of the forcible driving assistance and a driving assistance according to the notification may be performed, and the forcible driving assistance and a driving assistance according to the notification may be performed simultaneously. In addition, only one of the driving assistance for setting to the target speed Vtarget and the driving assistance for setting to the target side space W1target may be performed, both may be performed by staggering the timings, and both may be performed simultaneously.
When the blind spots exists in a plurality of directions as described in the present embodiments, the driving assistance control unit 31 may determine the danger direction with the high degree of danger, based on the danger zone DZ. For example, as illustrated in the graph of
In addition, the driving assistance control unit 31 may consider the viewing direction of the driver DP. The driving assistance control unit 31 acquires the detection result of the viewing direction detection unit 29, and determines whether or not the computed danger direction coincides with the driver's viewing direction. The driving assistance control unit 31 can weaken the driving assistance at the time when the driver turn to the danger direction and strengthen the driving assistance at the time when the driver does not turn to the danger direction, based on the determined result. For example, the driving assistance control unit 31 performs the control illustrated in
The processing of step S160 is ended, whereby the control processing illustrated in
Next, an operation and advantages of the driving assistance device 1 according to the present embodiment will be described.
In the driving assistance device 1 according to the present embodiment, the mobile object information setting unit 22 predicts a mobile object with the possibility of appearing suddenly from the blind spot, and sets the mobile object information regarding the mobile object. In addition, the speed zone computation unit 23 can compute the travel speed of the host vehicle having a possibility of the collision with the mobile object, based on the assumed speed of the mobile object predicted to rush out of the blind spot. Then, the speed zone computation unit 23 can compute the speed zone (danger zone DZ) that has a possibility of contacting the mobile object. The target speed computation unit 24 computes the target speed, based on the computed speed zone. In this way, the driving assistance device 1 does not compare the mobile object which is assumed with a course prediction result of the host vehicle SM, computes the speed zone that has the possibility of contacting the mobile object, and computes the target speed based on the computation of the speed zone. In this way, the driving assistance device 1 can perform the control based on the specific target speed indicating which speed is better to travel, and thus perform the driving assistance to ensure a high level of safety. In addition, the driving assistance of the driving assistance device 1 is not influenced by the accuracy of the course prediction of the host vehicle, and thus the driving assistance device 1 can perform an appropriate driving assistance. As described above, the driving assistance device 1 performs the appropriate driving assistance, and can improve the safety even more.
In addition, the driving assistance device does not perform the driving assistance from when detecting that the mobile object actually rushes out of the blind spot, and can perform the driving assistance by predicting the mobile object (and assumed speed) regardless of the actual rushing. When the blind spot passes through the intersection, the driving assistance device 1 computes the target speed after predicting the danger to be assumed in advance, and thus it is possible to perform the driving assistance to improve the safety even more, even when the mobile object actually rushes out of the blind spot.
The driving assistance device 1 includes the target lateral position computation unit 25 which computes the target lateral position of the host vehicle SM, based on the speed zone computed by the speed zone computation unit 23. The size of the blind spot is changed by the lateral position of the host vehicle SM, and thereby the degree of danger of contacting the mobile object is also changed. Thus, the driving assistance device 1 can perform the appropriate driving assistance in such a manner that the host vehicle SM can travel in a lateral position with a high level of safety, using the computation of the target lateral position performed by the target lateral position computation unit 25.
In the driving assistance device 1, the mobile object information setting unit 22 may set the mobile object information, based on the road shape forming the blind spot. The behavior of the mobile object having the possibility of appearing suddenly from the blind spot is influenced by the road shape. The driving assistance device 1 can perform the driving assistance with a higher accuracy, in consideration of the road shape.
In the driving assistance device 1, the mobile object information setting unit 22 may set the mobile object information, based on the ratio between a traffic lane width of the mobile object side and a traffic lane width of the host vehicle side. In this way, the driving assistance device 1 can perform the driving assistance which is more appropriate for the driver's sense and the actual rushing speed of the mobile object, in consideration of the ratio of the respective traffic lanes.
In the driving assistance device 1, the mobile object information setting unit 22 may set the mobile object information, based on the surrounding environment of the blind spot. In this way, in consideration of the surrounding environment of the blind spot, the driving assistance device 1 can perform the driving assistance which is more appropriate for the driver's sense.
The driving assistance device 1 includes the traffic information acquisition unit 26 which acquires the traffic information regarding the road configuring the blind spot. The mobile object information setting unit 22 may set the mobile object information, based on the traffic information acquired by traffic information acquisition unit 26. In this way, when passing through the blind spot road with a really high degree of danger, the driving assistance device 1 can perform a valid driving assistance that can improve the safety even more, in consideration of the traffic information that cannot be known only from the information around the blind spot.
The driving assistance device 1 includes the experience information acquisition unit 27 which acquires the past experience information of the driver. The mobile object information setting unit 22 may set the mobile object information, based on the experience information acquired by the experience information acquisition unit 27. In this way, the driving assistance device 1 can perform the driving assistance which is appropriate to the driver's experience, by using the past experience information of the driver.
The driving assistance device 1 includes the object information acquisition unit 28 which acquires the object information regarding the behavior of the object present around the host vehicle. The mobile object information setting unit 22 may set the mobile object information, based on the object information acquired by the object information acquisition unit 28. The behavior of the object around the host vehicle also influences the speed of the mobile object which rushes out or the like, but the driving assistance device 1 can perform the driving assistance which is appropriate to a more actual situation, in consideration of such information.
The driving assistance device 1 includes the driving assistance control unit 31 which calls the driver's attention to a blind spot. When a blind spot exists in a plurality of directions, based on the shape of the speed zone computed by the speed zone computation unit 23, the driving assistance control unit 31 may determine the danger direction with a high degree of danger, and control calling attention so that the driver can turn to the danger direction. In this way, the driving assistance device 1 performs calling attention in such a manner that the driver can turn to the danger direction with the high degree of danger, and thus the effect of preventing danger can be increased.
The driving assistance device 1 includes the viewing direction detection unit 29 which detects the viewing direction of the driver. The driving assistance control unit 31 may control the calling attention, based on the danger direction and the viewing direction. In this way, the calling attention is controlled by considering the viewing direction of the driver, and thus hassle to the driver is decreased and a further effective driving assistance can be performed in a situation where the driving assistance is actually required.
Furthermore, the driving assistance device 1 includes the target speed profile creation unit 32 which creates the target speed profile VPR for decelerating the host vehicle from the current speed Vnow to the blind spot entry target speed Vtarget at the time of entering the blind spot entry point SDL. Thus, the driving assistance device 1 can perform finally the driving assistance in which it is considered not only at which speed the host vehicle may enter the blind spot entry point SDL but also how much the host vehicle may decelerate while reaching there. Accordingly, a more appropriate driving assistance can be performed. As described above, the driving assistance device 1 performs an appropriate driving assistance and thus, the driving assistance device 1 can improve the safety even more.
In the driving assistance device 1, the target speed profile creation unit 32 can create the target speed profile VPR by computing the contact point T of the danger zone entry line DA which is the boundary line of the danger zone DZ, and the target speed profile VPR. For example, when the driving assistance is performed according to the target speed profile which avoids the danger zone DZ too much, there is a case where the driver feels cumbersome. However, since the target speed profile creation unit 32 creates the target speed profile VPR by computing the contact point T of the danger zone entry line DA of the danger zone DZ and the target speed profile VPR, the safety is ensured so as not to enter the danger zone DZ, and it is possible to suppress the cumbersome feeling due to an excessive driving assistance.
In the driving assistance device 1, the target speed profile creation unit 32 may create the target speed profile VPR, based on a constant target acceleration a, the first target position (L=L1) at which the speed of the host vehicle SM is set to the blind spot entry target speed Vtarget in front of the blind spot, and the second target position (L=L2) at which the deceleration according to the target acceleration a is started. Accordingly, the target speed profile creation unit 32 starts the deceleration according to a constant acceleration at the second target position (L=L2), and in a state of setting to the blind spot entry target speed Vtarget at the first target position (L=L1) in front of the blind spot, can create the target speed profile such as that for entering the blind spot. Accordingly, the driving assistance device 1 can perform the driving assistance in which the speed profile of the driver is realized with a high and safe driving technology.
In the driving assistance device 1, the target speed profile creation unit 32 may create the target speed profile VPR using at least one computation method, among the first computation method which computes the first target position (L=L1) and the second target position (L=L2) after the target acceleration a is set, the second computation method which computes the target acceleration a and the second target position (L=L2) after the first target position (L=L1) is set, and the third computation method which computes the target acceleration a and the first target position (L=L1) after the second target position (L=L2) is set, Accordingly, it is possible to create the target speed profile VPR using an appropriate computation method depending on the situation.
In the driving assistance device 1, the target speed profile creation unit 32 studies the characteristics of the driver, and may determine one computation method, among the first computation method, the second computation method, and the third computation method, based on the characteristics of the driver. Accordingly, it is possible to create the target speed profile VPR using an appropriate computation method depending on the characteristics of the driver, and to perform the driving assistance in which a sense of discomfort to the driver is reduced.
The present invention is not limited to the above-described embodiments.
For example, other vehicles are exemplified as the mobile object, but anything, having a possibility of appearing suddenly from the blind spot, such as a two-wheel vehicle may be used. Depending on the type of the mobile object, the mobile object information to be set is changed.
In addition, in the above-described embodiments, in order for the mobile object information setting unit 22 to set the mobile object information, various factors are considered, but all the factors are not required to be considered, and a portion or any one of the factors may be considered.
In the present embodiments, the danger zone DZ is set with respect to the distance of the host vehicle before the blind spot entry point, without particularly providing a range, but may be set as a limit with a constant range such as “0≦L≦×1”. In addition, the danger zone DZ may be set with respect to only a predetermined L, and the danger zone DZ may be set with respect to only the portion of L=0, for example (that is, the target speed is set based on only the speed zone at L=0).
In addition, the target speed profile may be created not only in the forms described in the present embodiments but also in all forms. For example, the target speed profile may not contact the danger zone entry line DA, and may be separated in order to further ensure the safety. In addition, the target acceleration may be set as a constant acceleration, but the target acceleration is set to multiple values and divided into several stages, and according to this, it may be decreased. The target acceleration may be changed gradually depending on the distance L.
The present invention can be applied to a driving assistance device.
1 . . . driving assistance device, 21 . . . blind spot recognition unit, 22 . . . mobile object information setting unit, 23 . . . speed zone computation unit, 24 . . . target speed computation unit, 25 . . . target lateral position computation unit, 26 . . . traffic information acquisition unit, 27 . . . object information acquisition unit, 29 . . . viewing direction detection unit, 31 . . . driving assistance control unit, 32 . . . target speed profile creation unit, SM . . . host vehicle, RM, LM . . . other vehicle (mobile object), DP . . . driver
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